Development of paper-based microfluidic device for the determination of nitrite in meat

This study employed the use of a microfluidic paper-based analytical device (µPAD) to determine the concentration of nitrite in pork and enhanced the limit of detection by analyzing the coffee-ring effect. The µPAD was fabricated by designing and embedding wax channels onto the cellulose-based filter paper through printing and subjecting the paper to heat treatment to allow wax penetration. Nitrite concentration was determined by monitoring the colorimetric reaction that occurred between nitrite and the added Griess reagent. The limit of detection of this device for nitrite in pork was determined to be 19.2 mg kg^-1 by analyzing the inner-chamber reaction, while it could be as low as 1.1 mg kg^-1 if the coffee-ring region was analyzed. The overall analysis could be completed within 15 min. This µPAD-based method has potential applications to routinely screen the nitrite concentration of meat products and ensure food safety and consumer health.